Last Light by M. Pierce

Matt Sky is missing. After a solo ascent of Longs Peak that left only a large blood stain, tatters of climbing clothing, and the tracks of an animal in the snow, he is presumed dead.

Hannah Catalano is guarding a secret: she knows Matt is alive. After Matt’s memorial service, she lingers on the East Coast with his family, but it soon becomes clear that his brothers’ motives are less than gracious. Nate Sky is bent on tracking down the author of Night Owl, a book that charts the last days of Matt’s life with uncanny and scandalous accuracy, and which appeared only after his death. Seth Sky is bent on getting Hannah into his bed.

Hidden away in the woods, Matt and Hannah strive desperately to maintain their ruse and their relationship–but their web of lies only tightens as Matt struggles with the consequences of his decision, and Hannah tries to escape Nate’s libel suit and fend off Seth’s advances…until Hannah is put in danger, and Matt must make a life or death choice.